World iron ore production consists primarily of hematite (Fe2O3) with simple open cut operations producing easily mineable and directly saleable products of lump and fines with iron content >63% Fe. Magnetite (Fe3O4) is also a readily available iron source but due to its low in-situ Fe values (30-40% Fe), requires additional upgrading to produce a marketable product.
WO 03/102250 describes the use of microwave energy to treat ores to facilitate subsequent processing of the ores to recover valuable components such as metals from the ores. The microwave energy caused some form of structural alteration of the ore particles without significantly altering the mineralogy, i.e. composition, of the ore. The structural alteration occurred as the result of differences in thermal expansion of minerals within ore particles, as a consequence of exposure to microwave energy, resulting in regions of high stress/strain within the ore particles and leading to micro-cracking or other physical changes within the ore particles. The micro-cracks improved leachability and susceptibility to subsequent comminution to reduce the particle size of the particles.